PAUL DIRAC wanted to be seduced, and he wasn’t afraid to admit it. In a 1963 essay recalling his role in discovering the strange-but-true laws of quantum theory, he wrote “it is more important to have beauty in one’s equations than to have them fit experiment”. That might sound odd. Experiment, after all, is the ultimate arbiter of an equation’s ability to explain natural phenomena. But for a theoretical physicist like Dirac, experiments could be misled: only beauty was incorruptible.

An almost religious devotion to beauty remains commonplace among theorists of fundamental physics, even if the standards of attractiveness have changed over time. One vision of elegance in particular has surged to the fore: the principle of naturalness. Broadly speaking, it is the belief that the laws of nature ought to be sublime, inevitable and self-contained, as opposed to makeshift and arbitrary.

Advertisement

But what if they aren’t? That’s the disquieting possibility being entertained by a growing band of physicists in the aftermath of what should have been the breakthrough discovery of the decade, the snaring of the Higgs boson in 2012. The discovery of the Higgs, at CERN’s Large Hadron Collider (LHC) near Geneva, Switzerland, confirmed a long-held theory about how particles acquire mass. But what we have – and haven’t – found alongside it could have profound consequences for how we view reality, says Michael Dine, a theorist at the University of California, Santa Cruz. “We might find that nature is not natural in the way we thought.”

Even among particle hunters, the word “natural” has a few …

Article amended on
9 March 2018

When this article was first published, we misquoted Gian Giudice, head of theory at CERN. We have removed the sentences in question.